Prevention of Significant Deterioration (PSD) and Nonattainment New Source Review (NSR): Aggregation and Project Netting

The EPA is taking final action on one part of the September 14, 2006 Federal Register proposed rule for the New Source Review (NSR) program. The purpose of the proposed rule was to clarify for sources and permitting authorities three aspects of the NSR program-- aggregation, debottlenecking, and project netting--that pertain to how to determine what emissions increases and decreases to consider in determining major NSR applicability for modified sources. This final action addresses only aggregation. This action retains the current rule text for aggregation and interprets that rule text to mean that sources and permitting authorities should combine emissions when activities are "substantially related." It also adopts a rebuttable presumption that activities at a plant can be presumed not to be substantially related if they occur three or more years apart. With respect to the other two components of the originally proposed rule, the EPA is taking no action on the proposed rule for project netting and, by way of a separate document published in the "Proposed Rules" section of this Federal Register, is withdrawing the proposed provisions for debottlenecking.